Pipeline construction



1966 F. H. POETTMANN 3,280,848

PIPELINE CONSTRUCTION Original Filed Jan. 15, 1962 SECTIONS OF PIPE GELLINING H I WEI-D/ FLUID BEING 9' TRANSPORTED PIPE WALL GEL LINING FLUIDBEING Fig. 2 TRANSPORTED United States Patent Ofiice 3,280,848 PatentedOct. 25, 1966 3,280,848 PIPELINE CONSTRUCTION Fred H. Poettmann,Littleton, Colo., assiguor to Marathon Oil Company, a corporation ofOhio Original application Jan. 15, 1962, Ser. No. 166,379, new PatentNo. 3,220,874, dated Nov. 30, 1965. Divided and this application Aug. 3,1965, Ser. No. 493,290 3 Claims. (Cl. 138145) The present application isa division of application Serial No. 166,379, filed January 15, 1962,now Patent No. 3,220,874.

This invention relates to pipe lines and control of pipeline fluid flowand more particularly relates to methods for increasing the maximum flowcapacity of pipe lines.

It is economically desirable to utilize pipe lines to their maximum flowcapacity. However, it is known that in continuous operation or afterextended periods of usage, pipe lines have their maximum flow capacityreduced due to corrosion and other conditions that roughen interiorpipeline flow contacting surfaces; including deposition of foreignmaterials and substances carried in the fluids (and particularlyliquids) being conveyed through a given line. Even under optimumconditions, the interior surface of a pipe line is relatively rough andoffers substantial impedance to flow.

Accordingly, it is an object of this invention to provide a simple,economical and eflicient method of increasing the maximum flow capacityof pipe lines.

It is another object of the invention to provide a simple, economicaland efiicient method of increasing the capacity of operating pipe linesafter reduced efliciency and flow capacity is detected.

It is still another object of this invention to provide a simple,economical and eflicient method of increasing the initial flow capacityof new pipe lines and adapting such lines for optimum performance overextended periods of usage.

Yet another object of my invention is to provide a simple, durable andefficient pipeline structure providing a high flow capacity in lines ofstandard diameter.

A further object of my invention is to provide a simple, economical andeflicient method of distributing a gelforming liquid as a thin film overa roughened interior surface of a pipe line and thereafter causing saidgel to form as a self-sustaining lining for the inner surface of theline which possesses a greater degree of smoothness than the originalinternal surface of such line.

Other objects reside in novel details of construction and novelcombinations and arrangements of parts, all of which will be detailed inthe course of the following description.

In one application, the practice of my invention is particularlyeffective in treating established pipe lines which are conducting fluidsat a capacity substantially less than optimum and which may beconditioned for operation at substantially optimum capacity. It is wellknown and can be demonstrated by the Moody friction factor chart thatthe pressure drop of fluids flowing in turbulent flow is a function onlyof the relative roughness, e/D, of a pipe confining such flow.

Thus, the smoother the inner surface of the pipe, the less the pressuredrop for a given flow rate will be. For example, in a given pipe sectionof six inch diameter, if

the pressure drop is held constant over a fixed length of such pipe andthe roughness is reduced from 0.0006 inch to 0.0001 inch, the flow ratewill be increased by approximately 25%; or if the flow rate is heldconstant and the roughness reduced from 0.0006 inch to 0.0001 inch, thepressure drop will be reduced by 40%.

According to this invention, such a decrease in relative roughness canbe accomplished in lines utilizing either single phase dry gas or singlephase liquid flow by lining the interior surfaces of the pipe with aspecially prepared gel to provide a very thin and extremely smoothfluidcontacting surface. The gel is stable and in the case of liquidflow may be made up from the same material as normally conveyed throughthe given pipe line. The gel lining may be applied by several methods.In one method, water, with a gelling agent added, such as Cyanogum 41,and including the retarder potassium ferricyanide, the catalyst systemB-dimethylaminopropionitrile ammonium persulfate and a surfactant suchas Triton X- is provided to increase the wettability of the pipe, bypassing such mixture through a pipe line while it is in a fluid stateand formed as a slug so as to completely wet the entire interior surfaceof the pipe line. After a'proper time period has elapsed which is basedon the gelling time for the fluid material deposited on the pipe walls,the fluid sets up, thereby providing a very thin and extremely smoothsurface lining for contacting the fluid flow through the pipe line.

Cyanogum 41 is a gelling agent manufactured by the American CyanamidCompany, and in essence, is a mixture of the two organic monomers,acrylamide and N,N-methylenebisacrylamide, in proportions which producevery stiff gels from dilute aqueous solutions when properly catalyzed.The process by which the gels are formed from the foregoing is apolymerization-crosslinking reaction. Triton Xl00 is a non-ionicsurfactant manufactured by Rohn & Haas Company and is octylphenoxypolyethoxy ethanol.

FIGURE 1 is a schematic illustration of an embodiment of the invention.

FIGURE 2 is a detail of the pipe line of FIGURE 1 showing the relativelyrough pipe wall covered by the relatively smooth gel lining.

In many instances it will be desirable to form a gel lining on theinterior of a pipe line conducting a hydrocarbon composition. In suchcases the hydrocarbon, which may be gasoline or fuel oil, for example,will have aluminum stearate or aluminum octoate added; and a slugthereof is passed through the pipe line to be lined in a manner similarto that above described. After the interior walls of the pipe line havebeen properly Wetted with the aluminum stearate or aluminum octoate andhydrocarbon system, they are catalyzed by raising the temperature toapproximately F. whereupon the desired gelling takes place and a smoothinterior lining forms on the wall surface.

In the case of older pipe line systems which are rather badly corroded,either of the foregoing procedures may be followed to provide a verysmooth interior lining, thereby greatly reducing the roughness of theliquid-contacting surface and providing substantially optimum flowcapacity for the pipe line so treated.

The gels which utilize the Cyanogum 41 material in an aqueous carrierare formed by the following two step process:

Step 1.An aqueous solution of Cyanogum 41 containing a retarder forcontrolling the gel time and the first component of the catalyst systemis prepared. In this example, the first catalyst component isB-dimethylaminopropionitrile and the retarder is potassium ferricyanide.

Step 2.-The second component of the catalyst system ammonium persulfateis added to the solution of Cyanogum 41 and retarder prepared accordingto the procedure set forth in Step 1. After a predetermined period oftime a stiff gel will form. However, the mixture remains quite fluiduntil this gel time is reached.

The following table sets forth alternative catalyst systems utilizingthe Cyanogurn 41 gelling agent:

In the foregoing procedures, I have described practices in which theinterior walls of a pipe line to be treated may be coated with or linedby the liquid system, before it gels, by passing a slug of a selectedcomposition through the pipe. Another system which also is applicable isdirected to the utilization of concentric flow techniques. In suchtechniques, porous or apertured annular members are mounted in the pipeline in encompassing relation to a section of pipe and a reservoir ofthe catalyst system is maintained under pressure about the porousmember. Fluid flowing through the pipe line in which the annular memberis inserted is encased or filmed circumferentially by the catalystsystem and is removed and deposited by TABLE I Liquid to be GelledGelling Agent Retarder 1st Catalyst Component 2nd Catalyst ComponentWater.. Cyanogurn 41. Potassium FerrieyanideB-dimethylaminoproplonitrile.. Ammonium persulfate (gel time= 2 200min.) Do. a do do Disodium phosphate Septahy- Ammonium persuliate (geldrate. time= 10-600 min.) Water or Glyeerine plus do Di-t butylperoxide(plus sur- Heat to 90 C. (or 5 min. gel

water or Ethylene Glycol factant to keep this material time). plusWater. well dispersed. Water do Ferrous ammonium sulfate Hydrogenperoxide (or 12 sec. gel

hexahydrate. time Do. do Sodium Thiosulfate Hydro en peroxide (gel time,14-15 min. Glycerine or Ethylene Glydo Ammonium persulfate (gel time,

As noted above, it is quite frequently desirable to add a surfactant tothe aqueous phase to enhance Wetting of the pipe wall. One such materialis the Triton X-lOO nonionic surfactant discussed above. However,anionic surfactants are equally effective. An example is Aerosol OTmanufactured by the American Cyanamid Company and which is sodiumdioctyl sulfosuccinate. Either of these materials is compatible with theCyanogum 41 gelling systems above noted and are excellent water wettingagents.

In the foregoing discussion, and in particular in the table set forth,approximate gel times are set forth. The relative length of time for anygiven system, of course, is further dependent upon the relativeconcentration of the various materials used. The Cyanogum 41 gellingagent produces very stiif gels from extremely dilute aqueous solutionswhen properly catalyzed. And, of course, stiffer gels are formed fasteras the relative concentration of the Cyano'gum 41 is increased. Thus,there are no particularly critical quantity ratios for the materialsused in the coating action according to the invention. The aluminumsoaps above noted which are used in the hydrocarbon carrier likewiseform a relatively stiff gel in dilute solutions.

Table I set forth above discloses the wide range of ingredients whichmay be employed in the instant method of increasing the capacity of pipelines. For some treatments wherein it is desirable to have a slow geltime, the second system will be particularly advantageous. In thissystem, disodium phosphate 'septahydrate is the first catalyst, ammoniumpersulfate, the second, while the same retarder potassium ferricyanideis used. Utilizing this system, a gel time from 1()600 minutes may beprovided. If a rapid gelling action is desired, the system utilizing ascomponents ferrous ammonium sulfate hexahydrate and hydrogen peroxide,which gels in only 12 seconds, is particularly useful. The slower geltime systems are preferable when the procedure of surface encasing of abody of flowing fluid is to be utilized.

While it has been suggested in the foregoing discussion that asurfactant be added to the aqueous phase to enhance the wetting of thepipe wall, it should be understood that such is not always necessary.This is particularly true when treating new pipes which do not have thevery roughened interior surface condition of many older installations.

Wiping on the interior surfaces of the pipe line through which the fluidflows.

One of the innovations of the pipe lining practices of my invention isthat the gelling material is introduced into the line as a liquid in acarrier solution and has suflicient wetting properties so that theentire interior surface of the line is wetted by its flow through theline. Such interior surface while seemingly smooth by usual standardsactually is a friction surface formed by a succession of peaks or 'hillsand valleys or pits and as such offers substantial impedance to flow.When such a surface corrodes, increasing irregularity results.Consequently, the wiping of such surfaces by the wetting liquid servesto fill and level the irregular surfaces and as gelling proceeds thematerial so introduced or deposited attains a stable, self-sustainingcondition and for practical purposes becomes a continuous adheringlining which is extremely smooth and so thin as to reduce the effectivediameter to only. a minute degree.

Any reduction in effective inside diameter is more than compensated bythe resulting increase in smoothness or evenness of theliquid-contacting surface of the lining. The gels employed for thispurpose are stable and will function efliciently during protractedperiods of operation. Therefore, they quickly restore the lostefliciency of established pipe lines and may be applied beforeinitiating operation of new pipe lines to render such lines capable ofoperating at substantially optimum efliciency. As the cost ofapplication is more than offset by the increased transport capabilitythey provide, such linings may be renewed whenever any substantialcapacity loss is detected. However, they are durable and functioneffectively over protracted periods of operation.

As a variety of ingredients have been shown as satisfactory in thepractice of my invention, selection of ingredien'ts may be made on acost or efliciency basis, and also from -a quick setting or slow settingpreference. Pipe lines treated in accordance with this invention willhave their maximum flow capacity increased by lessening their frictioneffect. In so doing, it is not necessary to separate joined pipesections as the slugs may be entered through available points ofintroduction in the line.

I claim:

1. A pipe line having increased flow capacity for transport of fluid,comprising a plurality of sections of pipe joined as a continuousconduit, and a substantially continnous lining on the internal surfaceof said line comprising a self-sustaining substantially permanent gelformed in adhering relation to interior surfaces of the succession ofpipe sections, said gel lining having an internal surface considerablysmoother than the internal surface of said sections.

2. A pipe line having increased flow capacity for transport of fluid,comprising a plurality of sections of pipe joined as a continuousconduit, and a substantially continuous self-sustaining substantiallypermanent gel lining on the internal surface of the line forming aninterior surface of substantially the same diameter as the initialdiameter of the line and characterized by a liquidcontacting surfaceconsiderably smoother than the internal surface of said sections.

3. A pipe line having increased flow capacity for transport of fluid,comprising a plurality of sections of pipe References Cited by theExaminer UNITED STATES PATENTS 1,605,574 11/1926 Stewart 138-1452,331,824 10/1943 Buckingham 138145X 2,602,760 Michel et al.

LAVERNE D. GEIGER, Primary Examiner. T. MOORHEAD, Assistant Examiner.

1. A PIPE LINE HAVING INCREASED FLOW CAPACITY FOR TRANSPORT OF FLUID, COMPRISING A PLURALITY OF SECTIONS OF PIPE JOINED AS A CONTINUOUS CONDUIT, AND A SUBSTANTIALLY CONTINUOUS LINING ON THE INTERNAL SURFACE OF SAID LINE COMPRISING A SELF-SUSTAINING SUBSTANTIALLY PERMANENT GEL FORMED IN ADHERING RELATION TO INTERIOR SURFACES OF THE SUCCESSION OF PIPE SECTIONS, SAID GEL LINING HAVING AN INTERNAL SURFACE CONSIDERABLY SMOOTHER THAN THE INTERNAL SURFACE OF SAID SECTIONS. 